Please check the links given below.

http://link.springer.com/article/10.1007/s10764-016-9890-4

https://www.researchgate.net/publication/227850895_Impact_of_global_warming_on_the_distribution_and_survival_of_the_gelada_baboon

https://www.researchgate.net/publication/256669157_Climate_Change_Predictive_Modeling_and_Lemur_Health_Assessing_Impacts_of_Changing_Climate_on_Health_and_Conservation_in_Madagascar

Article Impact of global warming on the distribution and survival of...

Article Climate Change, Predictive Modeling and Lemur Health: Assess...

I would suggest you should consider animal behaviours , change in feeding patterns, breeding, disease etc

I understand Arvind Sigh has given lot of information. Further biology of the study area has to be evaluated for climate change impacts.

Please see also the paper below.

http://orbi.ulg.ac.be/handle/2268/172232

there is so much publications on that - will suggest that you look at those papers including some that other colleagues have suggested.

In addition,for you to measure climate change impact on a primate species endemic to Niger delta you will need to   use time series data collection, imagery etc dating back to many decades   (the many the years the better!) to date.... 

Thank you all. Very helpful answers

The impact may be indirect. Direct changes of temperature and rainfall for example, may directly impact on the primate species and cause behaviour change, or may affect plant species they depend on. Different climate variables will have different impacts depending on the ecology -  climate change could benefit the primate species.